[asan] add experimental -asan-realign-stack option (true by default, which does not change the current behavior)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169216 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 92a678c..f095cff 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -115,6 +115,8 @@
cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
static cl::opt<bool> ClMemIntrin("asan-memintrin",
cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
+static cl::opt<bool> ClRealignStack("asan-realign-stack",
+ cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
cl::desc("File containing the list of objects to ignore "
"during instrumentation"), cl::Hidden);
@@ -1159,6 +1161,7 @@
// Filter out Alloca instructions we want (and can) handle.
// Collect Ret instructions.
+ unsigned ResultAlignment = 1 << MappingScale();
for (Function::iterator FI = F.begin(), FE = F.end();
FI != FE; ++FI) {
BasicBlock &BB = *FI;
@@ -1174,7 +1177,7 @@
if (AI->isArrayAllocation()) continue;
if (!AI->isStaticAlloca()) continue;
if (!AI->getAllocatedType()->isSized()) continue;
- if (AI->getAlignment() > RedzoneSize()) continue;
+ ResultAlignment = std::max(ResultAlignment, AI->getAlignment());
AllocaVec.push_back(AI);
uint64_t AlignedSize = getAlignedAllocaSize(AI);
TotalSize += AlignedSize;
@@ -1195,7 +1198,9 @@
Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
AllocaInst *MyAlloca =
new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
- MyAlloca->setAlignment(RedzoneSize());
+ if (ClRealignStack && ResultAlignment < RedzoneSize())
+ ResultAlignment = RedzoneSize();
+ MyAlloca->setAlignment(ResultAlignment);
assert(MyAlloca->isStaticAlloca());
Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
Value *LocalStackBase = OrigStackBase;